by Dennis Collin
Modelling stairs to a specific criterion is a common question when talking to architectural and structural users; specifically in getting stair landings to do what is required and trying to avoid those annoying error messages and warnings.
For this example, the Cast-in-place Stair, Insitu Concrete_150mm_Waist is used, but the principle works for any stair family. For other stair types it may be necessary to adjust landing thickness and offsets accordingly.
Fig 1. Automatic Stair tools are adequate for simple scenarios. (the minor handrail issue can be fixed later!)
When modelling stairs, most users use the automatic tools to generate a stair that will connect between the two levels. Stairs go up from a level to a target level or offset, and if necessary a landing can be sketched in to form the final connection, resulting in a stair as per figure 1.
Fig 2. Trying a complete this stair sketch results in an error!
However if a landing is also required at the bottom and a similar process attempted, then an error message displays as shown in figure 2.
For complex or bespoke stair scenarios it is recommended to use Revit’s classic sketching tools and draw a mix of riser and boundary lines to sketch our desired stair form.
Fig 3. Drawing stairs the traditional way, i.e. With lines!
Before doing so, ensure the level offsets and stair base and constraints are set. Sketch out the main stair run with linework as per fig 3, but do ensure when sketching that 2 riser lines remain, these will be used in an old Revit trick to form our landings as part of the stair run.
Fig 4. Ensure begin and end with riser is unticked!
Also, whilst drawing check that in the properties palette that the setting, start and end with riser, is unticked and draw some additional boundary lines to form landings top and bottom, with the two remaining riser lines drawn at both ends. As per figure 5.
Fig 5. Stair run sketch with “landings”.
Select each of the boundary lines for the landing and set the sloping options to ‘Flat’ rather than the default ‘Autodetect’ option. This can be accessed from the dropdown list in the options bar.
Fig 6. Setting sketch lines as Flat.
Click Finish and inspect the stairs in a suitable 3D view.
Although close, the result is not quite as desired, with the railings sloping at the bottom and the bottom landing slab needing to be thicker (or in some cases, even be present!). However, this is an easy problem to fix. Firstly, the lower landing!
Fig 7. Close but not bad, a few tweaks to the railings and lower landing is all that is required!
To fix the landing, select the Stair, edit the run and adjust the value of the Extend Below Tread base property to a suitable value (in our example -150mm).
To fix the railing, edit the railing sketch such as the railing following the landing is a separate line (use the split tool if required). Select the sketch line for the landing and set it to flat, in a similar way to the boundary lines for the stair run sketch (Ref Fig 6.)
Once complete, we’re done and hopefully the stairs will look like the result below. If not check the sketch line behaviour options for the stairs and railings has been set to ‘Flat’.
Fig 8. At last! A Revit stair starting and ending with a landing!
In summary, stair and railing families are some of the more complex Revit families, with settings and controls that are several levels deep in terms of dialogue boxes. Stair and Railing elements are a popular topic of discussion on Cadline’s follow-on and bespoke training courses. For more details visit https://training.cadline.co.uk/ and talk to one of the team who can help you with your requirements.
Comments (0 comments)